Aluminium alloy for lithographic sheet
The invention discloses an Al alloy suitable for processing into a lithographic sheet, the alloy having a composition in wt %: Mg 0.05 to 0.30, Mn 0.05 to 0.25, Fe 0.11 to 0.40, Si up to 0.25, Ti up to 0.03, B up to 0.01, Cu up to 0.01, Cr up to 0.03, Zn up to 0.15, unavoidable impurities up to 0.05 each, 0.15 total, Al balance. Also disclosed is a method of processing the Al alloy.
1 - 36 . (canceled)
37 . A method of processing an Al alloy having a composition in wt %:
Mg
0.05 to
0.30
Mn
0.05 to
0.25
Fe
0.11 to
0.40
Si
up to
0.25
Ti
up to
0.03
B
up to
0.01
Cu
up to
0.01
Cr
up to
0.03
Zn
up to
0.15
Zr
up to
0.005
Unavoidable impurities up to 0.05 each, 0.15 total Al balance,
which method comprises the steps of: casting, homogenising, optional hot rolling, cold rolling, and optional interannealing, wherein the homogenisation step is carried out by heating the cast alloy to a temperature of 550 to 610° C. for 1 to 10 hours and subsequently cooling to a hot rolling temperature of between 450 and 550° C.
38 . A method according to claim 37 , wherein the casting step is carried out by DC casting.
39 . A method according to claim 37 , which does not comprise the optional interannealing step.
40 . A method according to claim 37 , wherein the internnealing is batch interannealing.
41 . A method according to claim 40 , wherein the interannealing is carried out at 300 to 500° C. for 1 to 5 hours.
42 . A method according to claim 37 , wherein the interannealing is continuous internnealing.
43 . A method according to claim 42 , wherein the continuous interannealing is carried out at 450 to 600° C. for less than 10 minutes.
44 . A method according to claim 37 , further comprising the step of electrograining.
45 . A method according to claim 44 , wherein the alloy is electrograined in hydrochloric acid.
46 . A method according to claim 44 , wherein the alloy is electrograined in nitric acid.
47 . A method according to claim 44 , wherein the alloy is capable of being electrograined in both hydrochloric and nitric acids.
48 . A method of processing an Al alloy having a composition in wt %:
Mg
0.05 to
0.30
Mn
0.06 to
0.25
Fe
0.11 to
0.40
Si
up to
0.25
Ti
up to
0.03
B
up to
0.01
Cu
up to
0.01
Cr
up to
0.03
Zn
up to
0.15
Zr
up to
0.005
Unavoidable impurities up to 0.05 each, 0.15 total Al balance,
which method comprises the steps of: casting, homogenising, optional hot rolling, cold rolling, and optional interannealing, wherein the homogenisation step is carried out by heating the cast alloy to a temperature of 550 to 610° C. for 1 to 10 hours and subsequently cooling to a hot rolling temperature of between 450 and 550° C.